iDCalc helps with several daily computations utilized in radiation therapy and nuclear medicine. IDCalc is an function leaning to radiotherapists and medical physicists. It built in library of typical radiation beams with nominal energies from 2 MV to 50 MV. Conversion between several Radiation Quality specification indexes. It has equivalent square and equivalent diameter. Decay of frequently utilized isotopes from a calibration date to any future or present day. It has Percent Depth Dose (PDD) and Normalized Peak Scatter Factor (NPSF) .The user can calculate Percent Depth Dose (PDD) and Normalized Peak Scatter Factor (NPSF) for any energy in the valid quality range using d80 as the index to enter beam energy.